1. Field of the Invention
The present invention relates to a stereoscopic imaging optical system, an imaging device, and a camera, and in particular, relates to a stereo base variable type stereoscopic imaging optical system that includes two imaging lens systems, and an imaging device and a camera that include the stereoscopic imaging optical system.
2. Description of the Background Art
With recent increase in 3D television and movie contents, environments in which general users can easily view 3D (stereoscopic) video images have been being established. Along with this, with regard to imaging devices, cameras capable of taking 3D images have been proposed.
A 3D image can be taken with a pair of optical systems that are provided for forming images for a right eye and a left eye and that are arranged at an appropriate interval (stereo base). In addition, it is known that even with a light beam that passes through a single lens, an image formed by a light beam that passes through a right side of a pupil surface and an image formed by a light beam that passes through a left side of the pupil surface are individually obtained to generate a 3D image corresponding to right and left eyes.
Japanese Laid-Open Patent Publication No. 54-109432 discloses a method in which a color filter having different transparent wavelengths in right and left portions thereof is disposed on a pupil surface and an image is obtained.
Japanese Laid-Open Patent Publication No. 10-42314 discloses a method in which a right side image and a left side image are taken with a single lens at different timings.
Japanese Laid-Open Patent Publication No. 2006-208407 discloses a method in which a light beam divided at a pupil surface is guided by a relay optical system to an image sensor.
Japanese Laid-Open Patent Publication No. 2009-48181 discloses a camera in which an entire optical unit is moved by a detaching/attaching mechanism to adjust a stereo base.
Japanese Laid-Open Patent Publication No. 2009-210957 discloses a camera in which an entire optical unit is moved by a moving mechanism to adjust a stereo base.
Japanese Patent No. 3580869 discloses a method in which a diaphragm is moved in an optical axis direction in an endoscope to adjust a stereoscopic effect.
However, the technology disclosed in Japanese Laid-Open Patent Publication No. 54-109432 uses the color filter, and thus is not suitable for taking a color image. In the technology disclosed in Japanese Laid-Open Patent Publication No. 10-42314, time-division imaging is performed. Thus, an image of a moving object cannot be taken, and the imaging conditions are limited. In the technology disclosed in Japanese Laid-Open Patent Publication No. 2006-208407, the relay optical system is used. Thus, when the technology is applied to a so-called compact camera that generally takes snapshots and the like, the camera is made large in size. In each of the methods in these publications, the stereo base is short. Thus, when each method is applied to taking a snapshot of a person, it is difficult to obtain a sufficient stereoscopic effect. In the technology disclosed in Japanese Laid-Open Patent Publication No. 2009-48181, a stereo base value is selected only from discrete values. In the technology disclosed in Japanese Laid-Open Patent Publication No. 2009-210957, the minimum value of the stereo base is limited by the size of an outer frame of a barrel and thus is not sufficient for a need of taking an image of a close object. In the technology disclosed in Japanese Patent No. 3580869, it is possible to adjust the stereoscopic effect. In the method disclosed in this publication, a so-called convergence point is adjusted to move the reproduced position of an observed image forward or backward, and a sense of depth of a reproduced image cannot be adjusted by adjustment of the stereo base. In addition, the technology disclosed in Japanese Patent No. 3580869 provides design conditions suitable for an endoscope, and an optical system suitable for a compact camera cannot be obtained from the conditions disclosed in this publication.